With Sebastien Buemi and Jaime Alguersuari ousted by the energy drink's Faenza based secondary team after 2011, those most eligible juniors are now French rookie Vergne and his new Australian teammate Daniel Ricciardo.

At Jerez last week in the new STR7 car, their rivalry got off to a fascinating start.

By the end of the four days of running, their fastest laps were separated by no more than one hundredth of a second -- with Ricciardo enjoying the miniscule edge for the moment.

With a Red Bull seat up for grabs, 21-year-old Vergne admitted to RMC radio that the stakes are high.

But "There was not too much tension," he insists. "You have to forget about all those different aspects when you think about the work you need to do.

"We had four good days of testing. The engineers are working now for the next test in Barcelona at the end of the month.

"There is a competition with my teammate but at the same time we can't (let it) go in the wrong direction.

"You always want to beat everybody but my teammate is also the only other person who is working on the very same car as me," added Vergne.